Aiko jump roped for 20 minutes before stopping at 8:05. Just count 20 minutes back in order to see when she started.
8:05 - 20 minutes = 7:45
Given:
The power generated by an electrical circuit (in watts) as function of its current x (in amperes) is modeled by:

To find:
The current that will produce the maximum power.
Solution:
We have,

Here, leading coefficient is negative. So, it is a downward parabola.
Vertex of a downward parabola is the point of maxima.
If a parabola is
, then

In the given function, a=-12 and b=120. So,



Putting x=5 in the given function, we get




Therefore, 5 watt current will produce the maximum power of 300 amperes.
Volume prism= ½•a•c•h
=½•7•11•5
=½•385
=192.5cm³
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